Proteins do not work alone. Instead, they act as part of complexes, and complexes perform nearly every biological function in the cell. These complexes are held together via protein interactions. With the advent of complete genome sequences, the field of proteomics has developed, allowing proteins and their interactions to be studied on a large-scale basis. The YRC has focused on the analysis of protein complexes for nearly ten years. In doing so, they have developed technologies that have revolutionized the identification of proteins and protein interactions. Through hundreds of collaborations, they successfully applied these new technologies to an array of diverse biological questions. As proteomics comes of age, they will strive to remain at the forefront with a continued focus on protein interactions, advanced through collaborations with the biological community. Their goals are: to develop technologies to quantify proteins and to uncover the mechanisms by which protein interactions are regulated;to develop new affinity tags as well as high throughput methods that allow the identification of interactions without the use of affinity tags;to develop the potential of aptamers as an alternative set of protein specific reagents;to develop computational methods to predict protein interactions, which will proved large-scale function predictions that will be made publicly available for anyone to test;to improve fluorescence resonance energy transfer (FRET) which will allow the description of structures in their native context within living cells;and to combine FRET data with computational approaches in order to predict protein structure and interactions all the way to the atomic level. The multifaceted approach will develop the technologies needed to push biology forward, impacting not just the community of yeast biologists but also those working on all aspects of basic cell biology and human disease research.